Crackdown: Nobel peace laureate Shirin Ebadi said her sister Noushin was arrested and put in prison last night by security forces

Eight people died as security forces broke up the demonstrations, which Iran says were inspired and aided by the West.

Yesterday, Iranian foreign minister Manouchehr Mottaki summoned the ambassador after telling a press conference that the protesters ‘should not be encouraged by a few statements by certain countries’.

He added: ‘They should not pin their hopes on them. Britain will receive a slap in the mouth if it does not stop its nonsense.’

The Foreign Office said that at the meeting Mr Gass had responded ‘robustly’ to criticism of Britain’s call for Tehran to respect the human rights of Iranian citizens, but did not disclose what Iranian officials had said to him.

At least 20 opposition figures have been arrested since Sunday as hardline rulers crack down on Iran’s reform movement.

State media reported that thousands of government supporters staged a rally yesterday, calling for the punishment of opposition leaders for fomenting unrest after June’s disputed presidential election.

Abbas Vaez-Tabasi, a representative of Iran’s supreme leader Ayatollah Ali Khamenei, said last night that opposition leaders were ‘enemies of God’ who should be executed under the country’s sharia law.

Yesterday Foreign Secretary David Miliband criticised the Tehran regime following the anti-government protests.

Mr Miliband said the deaths were 'yet another reminder of how the Iranian regime deals with protest' and praised the courage of protesters.

At least 20 opposition figures have been arrested since Sunday as hardline rulers intensify a crackdown on Iran's reform movement.

The opposition Greenroad website reported journalist Mashallah Shamsolvaezin, a regular critic of the government, and university professor Noushin Ebadi - sister of the Nobel winner - were among seven arrested last night and sent to prison.

Shirin Ebadi, who won the Nobel peace prize for her human rights work in Iran, said she called her sister yesterday and Noushin was being punished because of that call.

She said: 'She was warned not to contact me. She is detained for the sake of me.

'She was neither politically active nor had a role in any rally. I am not aware of the place of her detention or the reason for her arrest.

'Over the last two months my sister has been summoned by the ministry of intelligence several times and asked to convince me to give up my human rights activities.

'She was also told to move from her house which is near my flat and they threatened to arrest her.'

Criticism: Opposition supporters stage a rally outside the Iranian embassy in London yesterday. Iran said today it will be summoning British ambassador Simon Gass over claims the West is supporting the Tehran protest

Violent: Iranian students in Rome hold a candlelit vigil after at least eight activists were killed during clashes in Tehran on Sunday

Courage: Protesters gather outside the Los Angeles Federal Building

Clash: An Iranian opposition supporter gestures after a police motorbike was set on fire during violent protests on Sunday

Others arrested included the son of a prominent ayatollah, a reporter for the opposition ILNA news agency and several activists.

Today, tens of thousands of government supporters attended rallies and called for the punishment of opposition leaders for inciting unrest, according to state media.

The elite Revolutionary Guard accused foreign media of supporting the opposition to harm the Islamic state.

A statement said: 'Trying to overthrow the system will reach nowhere... designers of unrest will soon pay the cost of their insolence.

'The opposition, which has joined hands with the foreign media, is backed by foreign enemies.'

Reformist Islamic Iran's Participation Front called on the country's rulers to apologise to the nation after the protesters were killed during violent clashes.

Yesterday, President Barack Obama praised 'the courage and the conviction of the Iranian people', while condemning the Islamic government for attacking demonstrators with 'the iron fist of brutality'.

National Security Council chief of staff Denis McDonough said the U.S. was exploring unilateral or UN sanctions to punish Iran for its refusal to halt uranium enrichment.

The exact death toll from Sunday's violence has not been confirmed. The government claims eight people were killed, but today Tehran's chief prosecutor said he was investigating only seven deaths.

The Iranian government has taken the bodies of five protesters, including the nephew of opposition leader Mir Hossein Mousavi, to prevent activists using their funerals as a platform for more demonstrations.

A total of 300 people were arrested in the protests, but where they are being detained has not been revealed.

Bloodied: Injured members of the Iranian security service shelter during clashes with opposition supporters

Mob: Activists wearing the trademark green ribbons of the opposition surround police officers during the protests while journalists and other figures critical of the Iranian government were arrested today